# 已知。邮件地址列表
# 目标。提取出名称、域名

email_list = ["123@exp.com", "456@exp.com", "789@exp.com"]

for mail in email_list:
    position = mail.index("@")  # 找出@的位置，用于切片
    user = mail[:position]
    domain = mail[position + 1 :]
    print(user, domain)
